Schorl


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schorl

[shȯrl]
(mineralogy)

Schorl

 

a mineral, a black ferruginous variety of tourmaline with isomorphic admixtures of magnesium, manganese, and trivalent iron (seeTOURMALINE). Schorl is found in granites, pegmatites, greisens, skarns, gneisses, hydrothermal veins, and various metamorphic shales.

References in periodicals archive ?
Schorl, monazite and zircon have been rarely observed in some hiddenite-bearing cavities.
Only lustrous terminated schorl crystals in kaolinized pegmatite and holmquistite in pegmatite contact schists have been abundant enough to be found in many collections.
From 1999 to 2006, some of the finest Namibian aquamarine, schorl and jeremejevite ever seen were collected in the Erongo Mountains, together with aesthetic fluorite, quartz, goethite pseudomorphs after siderite, and other important species such as cassiterite, ferberite and metazeunerite.
For example, the Desmond Sacco collection has a large half-"bowtie" schorl acquired in the late 1960's; the Natural History Museum in London has a plumbogummite from Krantzberg, purchased from well-known collector-dealer Charles Key in 1985; and one of us (BC) has a thumbnail schorl on granite matrix purchased in 1981 from Carlton Gems & Minerals in Johannesburg.
The schorl is highly lustrous and commonly shows complex habits and terminations.
In April-May of that year, schorl crystals up to 20 cm long in groups to 50 cm, the crystals displaying perfect trigonal symmetry, were collected.
Also, the granite hosts the miarolitic cavities that have produced the collectible aquamarine, schorl and other interesting minerals.
1939) described amygdules and geodes in the capping basalts, containing axinite, calcite, danburite, datolite, fluorite, goethite, hematite, pyrite, quartz, schorl and specular hematite.
The gray-white to brown greisenized rock is composed of quartz and topaz, with fluorite, schorl, and sericitic muscovite.
These are dark gray and consist of beryl, calcite, fluorite, goethite, quartz, schorl and topaz, with accessory ferberite, fluorapatite, muscovite, scheelite and serpentine (Diehl, 1992b).
Apart from the tungsten-tin deposits at Krantzberg, fluorite is associated with acicular schorl in vugs in an intrusive porphyritic dike 3.
Albite 2" consists of smaller crystals, up to 5 mm long, white to colorless; these are later, second-generation forms on previously crystallized minerals such as "albite 1," orthoclase, schorl and muscovite.